1. Field
The present inventive concept relates to a battery cell having a maximum internal space.
2. Description of Related Art
In general, secondary batteries may be rechargeable, have high capacity, and include nickel-cadmium (Ni—Cd) batteries, nickel-hydride (Ni—H) batteries, lithium-ion (Li-ion) batteries, and the like. Li-ion batteries, among the batteries described above, have received attention as next generation power sources due to excellent characteristics thereof, such as long lifespan, high capacity, and the like.
Li secondary batteries may have an operating voltage at a level of 3.6 V or higher and may be used to power portable electronic devices. Alternatively, several Li secondary batteries may be connected in series and be used in high-output hybrid vehicles. The use of Li secondary batteries has increased rapidly due to an operating voltage thereof, which is three times higher than that of Ni—Cd batteries or nickel-metal hybrid (N-MH) batteries, and relatively high energy density per unit of weight.
In general, Li secondary batteries may be manufactured based on battery cell units. In addition, according to a form of an exterior material, Li secondary batteries may be classified into can-type secondary batteries, in which an electrode assembly is embedded in a metallic can, and pouch-type secondary batteries, in which an electrode assembly is embedded in a pouch of an aluminum (Al) laminate sheet.
In general, the battery cells described above may be manufactured in such a manner that an electrolyte is injected thereinto, and an exterior material is sealed, with an electrode assembly included in the exterior material.
FIG. 1 is an exploded perspective view of a composition of a related art pouch-type battery cell, while FIG. 2 is a perspective view illustrating an assembled state of the battery cell illustrated in FIG. 1. In addition, FIG. 3 is a cross-sectional view taken along line I-I′ of FIG. 2.
With reference to FIGS. 1 to 3, the related art pouch-type battery cell may generally include an electrode assembly 10 and a pouch-type case 20 including the electrode assembly 10.
In this case, the electrode assembly 10 may include an electrode plate, that is, an anode plate and a cathode plate. In addition, a separator (not illustrated) may be interposed between the anode plate and the cathode plate. Furthermore, each of the anode plate and the cathode plate may include one or more electrode taps 11, that is, an anode tap and a cathode tap.
The anode tap and the cathode tap may be connected to an electrode lead 12, that is, to an anode lead and a cathode lead, respectively. In addition, a portion of the anode lead and the cathode lead may be exposed outwardly of the pouch-type case 20, thus acting as an electrode terminal in order to be electrically connected to an external component of a secondary battery, that is, a different secondary battery or an external device.
The electrode assembly 10 may be formed to have a stacked structure, as illustrated in FIG. 1. In this case, a stacked electrode assembly refers to an electrode assembly having a structure in which a plurality of anode plates and cathode plates are included and are alternately stacked, with the separator interposed therebetween.
A case 20 may include an upper case 21 and a lower case 22. In addition, the electrode assembly 10 and an electrolyte may be included in an internal space formed by the upper case 21 and the lower case 22. In the upper case 21 and the lower case 22, a sealing portion S may be formed along an edge thereof in order to seal the internal space. In addition, the sealing portions S may be bonded (sealed) to each other, thus sealing the internal space.
The case 20 may be formed to have a form in which an Al thin film is included, in order to protect an internal component, such as the electrode assembly 10, the electrolyte, and the like, as well as to supplement electrical and chemical properties and improve heat dissipation properties thereof by the electrode assembly 10 and the electrolyte.
In addition, the Al thin film may be interposed between insulating layers, formed using an insulating material, in order to have electrical insulating properties with respect to the internal components of the secondary battery, such as the electrode assembly 10 and the electrolyte, or a different component on an exterior of the secondary battery.
However, a related art pouch-type case may not have a relatively high level of hardness. Therefore, as illustrated in FIG. 3, in a process of injecting the electrolyte thereinto, and discharging gas therefrom, a problem in which a form of a case collapses and is crushed may occur (see arrows).
In a case in which the form of the case collapses, the internal space of the case may not be maintained, but may be reduced. Therefore, a problem in which a space to be filled with the electrolyte is also reduced may occur.